Re: Why doesn't Mathematica solve this simple differential equation?

*To*: mathgroup at smc.vnet.net*Subject*: [mg69290] Re: Why doesn't Mathematica solve this simple differential equation?*From*: Joseph Gwinn <JoeGwinn at comcast.net>*Date*: Tue, 5 Sep 2006 05:31:10 -0400 (EDT)*Organization*: Gwinn Instruments*References*: <eddqq8$3vq$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

In article <eddqq8$3vq$1 at smc.vnet.net>, Joseph Gwinn <JoeGwinn at comcast.net> wrote: > Here is the system I'm trying to solve. It's an electrical circuit > consisting of a capacitor C1 (with initial voltage 4.0 volts), a > resistor R1, and a diode in series. I just read the Mathematica 5.2 NDSolve Advanced Documentation section on Differential Algebraic Equations. It occurs to me that, aside from the typos, what may be happening is that I'm handing Mathematica something that looks like a Differential Algebraic Equation (DAE) of index exceeding 1, as Mathematica was able to solve the system with one implicit equation (for the diode, with a capacitor but no resistor). Joe Gwinn